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B Hoch

Publications and source records attributed to B Hoch.

33 records · Page 2Linked to original sources
PubMed1994

Inefficient rpl2 splicing in barley mutants with ribosome-deficient plastids.

Analysis of transcript accumulation and splicing in plastids of four nuclear mutants of barley revealed that the ribosomal protein L2 (rpl2) gene transcripts containing a group II intron remained entirely unspliced, whereas the intron of the ribosomal protein L16 (rpl16) gene (linked with the rpl2 gene in the same operon) was removed in the mutant plastids. Also, the transcripts of other genes containing group II introns (ribosomal protein S16 gene, rps16; NADH dehydrogenase ND2 gene, ndhB; cytochrome f gene, petD; and intron-containing reading frame 170, irf170) and of the tRNA for leucine, trnL (UAA), possessing the only chloroplast group I intron, were found to be spliced. The mutants used in this investigation are considered to be nonallelic; this excludes the possibility that a single nuclear gene is responsible for the impaired splicing of rpl2 transcripts. The mutants, however, have a severe deficiency in chloroplast ribosomes in common; this deficiency is evident from the lack of the essential ribosomal protein L2 and from an extremely low steady state level of plastid rRNAs. From these results, we conclude that a functioning translational apparatus of the organelle is a prerequisite for splicing of the chloroplast rpl2 class II intron but not for splicing of at least five other group II intron-containing transcripts. This provides genetic evidence for a chloroplast DNA-encoded component (e.g., a maturase) involved in the splicing of rpl2 pre-mRNA.

Base Sequence↗
PubMed1993

RNA editing in maize chloroplasts is a processing step independent of splicing and cleavage to monocistronic mRNAs.

The psbB operon contained in the plastomes of higher plants consists of the genes psbB, psbH, petB and petD. The primary transcript of this operon is subject to a series of processing steps which include cleavages resulting in four monocistronic mRNAs and splicing of the petB and petD transcripts. A search for editing sites within the two latter transcripts from maize led us to the detection of one editing site within the petB coding region which is conserved at the DNA level in other graminean species and in tobacco. This shows that editing must be considered as an additional processing step of the psbB operon encoded primary transcript. As is evident from cDNA sequences derived from the dicistronic and/or unspliced petB/D transcripts which are completely edited, editing is an early step of mRNA processing which precedes both splicing and cleavage to the monocistronic mRNAs and which must, therefore, be independent of the latter two steps. This conclusion is confirmed by a similar observation with the editing site of the rpl2 transcript which is contained in the polycistronic transcript of the rpoA operon, although here only partial editing is observed for the unspliced dicistronic rpl23/rpl2 transcript.

Animals↗
PubMed1993

[Sleep analysis computer in diagnosis of sleep-related respiratory disorders].

Sleep related breathing disorders influence the structure of sleep by considerably modifying the ratios of the individual sleep stages. The sleep analyses carried out by polysomnography in the diagnosis of sleep related breathing disorders have so far been evaluated manually according to the criteria of Rechtschaffen and Kales, since automatic systems do not permit standardised evaluation as yet. Automatic sleep analyses via SAC, however, has been developed further in recent years and has widened its scope and efficiency. It is now possible to perform a comprehensive sleep analysis via SAC by means of modified criteria after Rechtschaffen and Kales. The SAC determines individual curves in the EEG and EOG and includes in addition to the EEG parameters an automatic apnoea detection as well as detailed breathing and oxygen saturation analyses. The Sleep Analysis Computer (SAC) records 15 parameters (2 EEG, 2 EOG, 2 EMG, ECG, NAF, thoracic and abdominal breathing curves, oxygen saturation, body posture, optionally blood pressure = RR, CPAP etc.). This means that all the parameters required for diagnosing sleep related breathing disorders as well as their differential diagnosis can be determined. Within the framework of a blood pressure study, 16 patients (average 45.5 SD 4.6 years) were subjected to SAC measurement in addition to conventional PSG. The computer recordings were evaluated according to apnoea index, the form of the apnoea and the oxygen saturation desaturations. The evaluation yielded the following pattern: 4 patients with AI < 10, 8 patients with AI between 10 and 20, 4 patients with AI > 20. Obstructive apnoeas were seen in 6 patients, mixed apnoeas in 8 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebral Cortex↗
PubMed1992

Identification of editing positions in the ndhB transcript from maize chloroplasts reveals sequence similarities between editing sites of chloroplasts and plant mitochondria.

A comparison of the nucleotide sequences from genomic DNA and cDNA of the ndhB gene from maize chloroplasts shows that the ndhB transcript is edited by C-to-U transitions at six positions which appear to exist as editing sites also in the chloroplast ndhB genes from rice and tobacco but not from liverwort. In order to identify possible sequence determinants necessary for editing, the sequences surrounding the newly identified ndhB and previously identified ndhA editing sites were compared with each other and with editing sites observed in plant mitochondrial transcripts. Among the chloroplast editing sites two closely positioned ndhB sites show similarity by sharing a common octanucleotide. The existence of the identical octanucleotide in the ndhJ gene whose transcript is not edited at the respective position, shows, however, that this octanucleotide is not sufficient to elicit the editing process. On the other hand, several of the chloroplast editing sites show sequence similarities with certain sets of consensus sequences reported earlier for editing sites of plant mitochondria. This supports the view that the editing processes of both plant organelles share common components and/or mechanistic steps and that the consensus sequences are part of the determinants necessary for editing.

Amino Acid Sequence↗
PubMed1992

Internal editing of the maize chloroplast ndhA transcript restores codons for conserved amino acids.

The NADH dehydrogenase subunit A (ndhA) gene from maize chloroplasts encodes a highly conserved peptide, which at several positions could be restored to consensus sequences by potential C-to-U editing of the codons involved. This gene was, therefore, chosen for analysis of its mRNA sequence in the form of amplified cDNA. A comparison of this cDNA sequence with the plastome-encoded ndhA sequence reveals four C-to-U editing sites, thereby demonstrating as a novel finding that chloroplast editing can also affect internal mRNA positions. All the edited codons restore amino acids that are conserved in the ndhA-encoded peptides of other chloroplast species. Alignment with homologous mitochondrial NADH-ubiquinone reductase subunit 1 (nad1) sequences of plant and even nonplant species shows that two of the editing positions restore universally conserved amino acids and that one editing site is even shared with nad1 mRNA of plant mitochondria. No editing sites could be detected in the cDNA derived from transcripts of the maize chloroplast RNA polymerase alpha-subunit (rpoA) gene.

Amino Acid Sequence↗
PubMed1991

Editing of a chloroplast mRNA by creation of an initiation codon.

Primary mRNA transcripts in several systems are edited by single base substitutions, small deletions or insertions to yield functional messenger RNA species. Mitochondrial mRNAs in particular, including those from plants, seem to be the subject of extensive editing, unlike mRNAs encoded by chloroplast DNA, for which the prediction of amino-acid sequence from the corresponding gene sequence is generally unambiguous. Occasionally, however, an ACG codon appears at the 5' terminus of chloroplast genes, where the initiation codon ATG would be expected. Here we present evidence for a C----U editing that is responsible for the conversion of the ACG codon to an AUG initiation codon in the mRNA transcript from the rpl2 gene of the maize plastome, showing that mRNA editing can also occur in chloroplasts.

Amino Acid Sequence↗
PubMed1991

[Assessment of the MESAM and Biox 3700 early warning methods for the diagnosis of sleep-related respiratory disorders in young men].

We can use pulse oximetry as a method for diagnosis of the sleep apnoea syndrome, as well as L-EKG, MESAM II and the actigraph. In this study MESAM II and pulse oximetry were combined for finding out discrete sleep-related breathing disorders. The results were compared with polysomnography. 5 (15.1%) of 32 patients had an index of apnoea (AI) greater than 10, whereas 4 (12.1%) patients showed an AI greater than 5. All of the patients with positive signs in MESAM II/pulse oximetry had an AI greater than 5 in polysomnography, whereas non of the patients with negative signs in MESAM II/pulse oximetry had an AI greater than 5 in polysomnography.

Adult↗
PubMed1990

Alternative base pairing between 5'- and 3'-terminal sequences of small subunit RNA may provide the basis of a conformational switch of the small ribosomal subunit.

The compiled sequences of small subunit ribosomal RNAs have been screened for base complementary between 5'- and 3'-terminal regions. Highly conserved complementary sequences are found which allow formation of a helix between the two ends of 5 or 6 base pairs. This helix is composed of sequences from the loop region of the first 5'-terminal stem and from sequences immediately distal to the last stem (the Me2A-stem) of the 3' terminus and therefore allows a coaxial stacking with either of these two flanking stems. Formation of the 5'/3'-helical arrangement is, however, only possible at the cost of dissolving the 'pseudo-knot' helix between the 5'-terminal region and the internal region of small subunit RNA. It is postulated that the mutually exclusive conformational states are in dynamic equilibrium and that they correlate with distinct functional states of the small ribosomal subunit. The 'pseudo-knot' containing conformation with the 3'-terminal sequences more exposed is likely to represent the initiating state, whereas the 5'/3' terminal paired 'closed' conformation may represent the elongating state in which interaction with fortuitous ribosomal binding sequences of mRNAs is avoided.

Base Composition↗
PubMed1984

Sinusitis caused by Legionella pneumophila in a patient with the acquired immune deficiency syndrome.

A patient with the acquired immune deficiency syndrome and Legionella pneumophila infection of the maxillary sinus is described. The organism was identified by direct immunofluorescence staining of sinus tissue. Because the Legionella species are intracellular pathogens, it is not surprising that this patient with a cellular immune defect was infected. However, no other site of Legionella infection was found. This appears to be the first reported case of upper respiratory tract infection by a Legionella species.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

HSP25 in isolated perfused rat hearts: localization and response to hyperthermia.

Recent investigations concentrate on the correlation between the myocardial expression of the inducible 70-kDa heat shock protein (HSP70i) by different stress conditions and its possible protective effects. Only few studies have focused on the involvement of small heat shock proteins in this process. We analyzed the location of the small heat shock protein HSP25 in isolated cardiomyocytes as well as its location and induction in isolated perfused hearts of rats. By immunofluorescence microscopy HSP25 was found to colocalize with actin in the I-band of myofibrils in cardiomyocytes of isolated perfused hearts as well as in isolated neonatal and adult cardiomyocytes. Hyperthermic perfusion of isolated hearts for 45 min resulted in modulation of different parameters of heart function and in induction of HSP25 is constitutively expressed even in normothermic perfused (44-46 degrees C) were lethal with respect to the contractile function of the hearts. Compared to control hearts perfused at 37 degrees C, significant increases during hyperthermic perfusion at 42 degrees C and 43 degrees C were obtained for heart rate, contraction velocity and relaxation velocity. In response to hyperthermia at 43 degrees C and after subsequent normothermic perfusion for 135 min at 37 degrees C, left to control values immediately after the period of heat treatment. HSP25 is constitutively expressed even in normothermic perfused hearts as shown by Western blotting. Hyperthermia increased the content of HSP25 only in the left ventricular tissue. In contrast, HSP70i was strongly induced in all analyzed parts of the myocardium (left ventricle, right ventricle, septum). Our findings suggest a differential regulation of HSP25 and HSP70i expression in response to hyperthermia in isolated perfused hearts. The constitutively expressed HSP25 seems to be located adjacent to the myofibrils which implies a specific role of this protein even under unstressed conditions for the contractile function of the myocardium.

Animals↗
PubMedDate not supplied

Bilateral diaphragmatic paralysis after cardiac surgery: ventilatory assistance by nasal mask continuous positive airway pressure.

The case of an 8-month-old boy with bilateral diaphragmatic paralysis after surgical reoperation for congenital heart disease is presented. In order to avoid repeated intubation and long-term mechanical ventilation or tracheotomy, we used nasal mask continuous positive airway pressure (CPAP) as an alternative method for assisted ventilation. Within 24 hours the boy accepted the nasal mask and symptoms such as dyspnea and sweating disappeared. Respiratory movements became regular and oxygen saturation increased. Nasal mask CPAP may serve as an alternative treatment of bilateral diaphragmatic paralysis in infants, thereby avoiding tracheotomy or long-term mechanical ventilation.

Diaphragm↗